This invention relates to sheet coating and drying apparatus and more particularly to paper sheet coating and drying apparatus which uses a simple and efficient configuration for coating the lower surfaces of paper sheets with lacquer or other coating liquid and which then efficiently uses air streams created by fans to simultaneously dry the lower surfaces of the coated paper sheets while holding or supporting the paper sheets upwardly against a conveyer as the paper sheets pass through the apparatus.
When one side of paper sheets, such as photographic paper sheets, are to be coated with a liquid, such as lacquer, it is most efficient to provide the coating liquid to the paper sheets from below the paper sheets so that the lower sides of the sheets are the sides that are coated. This is true because it is more difficult and less efficient to handle and move a coating liquid in a manner relative to the sheets so that the top surfaces of the sheets are coated. Applying a coating liquid to the tops of the sheets requires more complicated mechanisms than are required for coating the lower surfaces of the sheets.
When the lower sides of sheets are coated, however, drying of the lower sides of the sheets becomes difficult with known coating and drying machines. This is because the lower, wet sides of the sheets cannot be permitted to contact a conveyer or any other structure used to transport the sheets through the machine or to eject the coated sheets from the machine until the sheets are dried.
Various types of coating machines are known for use in coating and drying paper sheets. However, none of the known machines use gas or air streams for simultaneously drying lower surfaces of the paper sheets and for supporting the paper sheets as the sheets pass through the machine. Also, known machines have not proved entirely satisfactory under all conditions of service because it is often difficult to maintain uniformity in the lacquer mixture used to coat the paper during the coating process and it is often difficult and time-consuming to clean lacquer from the internal working mechanisms of the machines.
It is, therefore, an object of the present invention to provide an apparatus and method for coating and drying paper sheets.
Another object is to provide such an apparatus and method which efficiently uses the force of air generated by fans to simultaneously dry the paper sheets and to support the paper sheets against a conveyer as the sheets are transported through the apparatus.
A further object of the invention is the provision of such an apparatus and method which recirculates lacquer or coating liquid to maintain uniformity of the lacquer or coating liquid during operation of the apparatus.
Still another object is to provide such an apparatus and method which includes a simple and expedient configuration for quickly and easily washing and cleaning internal parts of the apparatus which become covered with lacquer or other coating liquid.
Another object is to provide such an apparatus and method which coats lower sides of paper sheets, such as photographic paper sheets, and which simultaneously dries the paper sheets and supports the paper sheets by use of air streams as the sheets move through the apparatus.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages are realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.